U.S. Pat. Nos. 5,018,353 and 5,111,661 disclose master cylinders wherein compensation between a first chamber in a bore of a housing and a reservoir occurs through a single center port compensation valve associate with a first piston and between a second chamber in the bore through a relationship established between a radial port and sealing structure carried on a second piston. In order to eliminate the possibility of cutting a nub in a seal by extrusion into the radial port, U.S. Pat. Nos. 5,207,062 and 5,279,125 disclose the use of a second center port compensation valve through which compensation is achieved for the second operational chamber in a bore. In master cylinders having such separate compensation valves for the first and second pressurizing chambers in the bore communication typically occurs through ports from separate passages in the housing when the first and second pistons are in a rest position. As the first and second pistons approach the rest position, stop pins engage the compensation valves to open the compensation valve and initiate communication between the reservoir and bore. Unfortunately, the passage required the rear piston is quite long as the compensation port needs to be located adjacent the end of the housing for the master cylinder. In addition, when such master cylinders are recessed into a front chamber of a vacuum brake booster care needs to be taken with respect to sealing structure to assure that vacuum does not draw fluid into the vacuum brake booster.